1. Field of the Invention
The present invention relates to a closure device for medical specimen collection containers and more specifically, to an improved closure disk for effecting reseal in punctured blood collection tubes.
2. Description of Related Art
Blood samples and other medical specimens are routinely taken and collected in a specimen collection container. With blood samples, the container is typically in the shape of a hollow tube with one end closed by a semi-spherical portion and the other end open. The open end is sealable by a cover. The tube thus defines an interior chamber for collecting and holding the blood sample.
Blood collection tubes can be formed with a vacuum chamber allowing the interior of the container to be at zero or lower-than-ambient pressure. It is well known that such a vacuum facilitates the drawing of blood from a body. Once the cover is punctured by a probe or needle drawing a medical sample, the vacuum will be released.
The cover is typically made of an impervious elastomeric material which is penetrable by a hollow probe or needle through which the blood sample is delivered to or removed from the chamber. Friction between the elastomeric cover material surrounding the needle and the needle surface performs a wiping function that wipes blood from the exterior surface of the needle as the needle is withdrawn from the chamber. The elastomeric cover also tends to reseal the hole produced by the needle to prevent leakage after the needle is withdrawn from the cover. The cover is typically held in place by either an interference fit between the tube and the cover or by adhesively affixing the cover to the open end of the tube.
Even though the cover material is sufficiently elastomeric so as to close in on itself and seal the probe opening to a certain extent when the probe is removed, the hole though which the probe is withdrawn has the potential to permit blood leakage in the event that the tube is mishandled or otherwise comes to rest in an inverted or non-upright position. Multiple punctures in the cover will compound this problem. In some instances a single needle will penetrate and withdraw from several tubes such as during the taking of multiple blood samples from a single patient. In these instances it is important that the probe be thoroughly wiped as it is withdrawn from each tube. This prevents the probe from depositing some non-wiped sample on the exterior surface of any subsequently-punctured covers and also prevents exposure of a non-wiped needle to the phlebotomist. Similarly, the cover of a single tube may be penetrated several times during the course of taking a blood sample and subsequently removing all or some of the blood sample for analysis. In these cases it is important that cover be able to continue to reseal so that cover integrity is maintained.
The cover performs a critical safety role in that it must ensure that the sample taken does not in some way escape the tube by either adhering to the needle or by leaking out the opening the probe creates after penetrating the cover. Therefore the cover should adequately reseal the opening and wipe the needle clean as it withdraws so that no sample is exposed to the phlebotomist or the health care worker directly from the needle or by the leakage through the opening created by the needle puncture.
As the safety of the health care workers and the preservation of the samples are of paramount interest, it is therefore desirable to provide a closure for a medical specimen collection container that provides higher safety through improved reseal and wiping characteristics.